نتایج جستجو برای: vaca c
تعداد نتایج: 1057856 فیلتر نتایج به سال:
Naturally occurring noncytotoxic vacA type s2 strains of Helicobacter pylori have a 12-residue extension to the vacuolating cytotoxin (VacA) compared with cytotoxic type s1 strains. We show that adding the region encoding this extension to type s1 vacA completely abolishes vacuolating cytotoxin activity but has no effect on VacA production.
Allelic variation among Helicobacter pylori vacA occurs in the signal and middle region of the gene. The aim of the study was to investigate alleleic variation of vacA among H. pylori strains from three regional areas of China and the relationship between vacA alleles and PUD. DNA extracted from 88 clinical isolates of H. pylori was analyzed by type-specific PCR and reverse hybridization line p...
Virulence mechanisms underlying Helicobacter pylori persistence and disease remain poorly understood, in part, because the factors underlying disease risk are multifactorial and complex. Among the bacterial factors that contribute to the cumulative pathophysiology associated with H. pylori infections, the vacuolating cytotoxin (VacA) is one of the most important. Analogous to a number of H. pyl...
Background: Helicobacter pylori has been classified as the class I carcinogenic agent by world health organization. Colonization of the human stomach with H. pylori is a risk factor for gastroduodenal diseases. The secreted vacA toxin is an important H. pylori virulence factor that causes multiple alterations in gastric epithelial cells and T cells. Several families of vacA alleles have been de...
The VacA toxin secreted by Helicobacter pylori enhances the ability of the bacteria to colonize the stomach and contributes to the pathogenesis of gastric adenocarcinoma and peptic ulcer disease. The amino acid sequence and structure of VacA are unrelated to corresponding features of other known bacterial toxins. VacA is classified as a pore-forming toxin, and many of its effects on host cells ...
OBJECTIVE Prior reports suggested that infection with Helicobacter pylori was associated with respiratory diseases; pathogenetic mechanisms however, were not defined. We tested the hypothesis that VacA, an exotoxin of H. pylori, a gastric pathogen, was aspirated into the lung and could stimulate secretion of inflammatory cytokines by lung epithelial cells. METHODS The presence of VacA was det...
The major secreted virulence factor of Helicobacter pylori, the vacuolating cytotoxin VacA, is known to insert into eukaryotic membranes and has been observed in association with the surface of H. pylori cells that are actively producing it. Here, it is demonstrated that VacA is capable of interacting with the surface of H. pylori and Escherichia coli after secretion. It is shown that this inte...
Background: Helicobacter pylori vacA (vacuolating toxin A) gene is comprised of mid- (m), intermediate- (i) and signal-regions. Recently, the vacA-i region genotype has been suggested to be a better predictor of disease severity than either the s- or m-region. The main aim of the present study was to determine the associations of i region poly-morphisms of vacA gene with gastric cancer (GC) and...
The predominant Helicobacter pylori strains circulating among geographic locations differ in regard to genomic structure. The association of the cagA-positive, vacA s1 genotypes with peptic ulcer disease (PUD) and gastric cancer was reported in Western countries but not in East Asian countries. Strains from Western countries predominantly possessed cagA type 2a, vacA s1a or s1b/m1a, or vacA m2a...
Helicobacter pylori bacteria colonize the human stomach where they stimulate a persistent inflammatory response. H. pylori is considered noninvasive; however, lipopolysaccharide (LPS)-enriched outer membrane vesicles (OMV), continuously shed from the surface of this bacterium, are observed within gastric epithelial cells. The mechanism of vesicle uptake is poorly understood, and this study was ...
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